The detection of a wide range of analytes present in fluid samples is of great importance in the diagnoses and maintenance of certain physiological abnormalities. Quantitative analysis of analytes in bodily fluids, for example, is necessary for the detection, management, and treatment of many degenerative medical conditions. For example, lactate, cholesterol, and bilirubin should be monitored in certain individuals. In addition, determining glucose in body fluids is important to diabetic individuals who must frequently check their blood glucose levels to regulate the carbohydrate intake in their diets. Failure to monitor glucose levels and take corrective action can have serious implications for a diabetic individual. When blood glucose levels drop too low—a condition known as hypoglycemia—a person can become nervous, shaky, and confused, and may become physically impaired and eventually pass out. A person can also become very ill if their blood glucose level becomes too high—a condition known as hyperglycemia—which, like hypoglycemia, is a potentially life-threatening condition.
Many conventional hand-held glucose testing devices (“meters”) utilize test strips that provide an indication of the presence and/or concentration of a particular substance within the body fluid being analyzed. These test strips are often thin strips of material, such as paper or plastic, which are coated or impregnated with a chemical reagent. A reagent is a substance or compound that is used to detect, measure, examine, or produce other substances by chemically reacting with a given substance present in a test sample. When the test strip comes into contact with a body fluid, such as blood or interstitial fluid, the test strip “harvests” the body fluid, e.g., fluid is drawn into a capillary channel that transfers the fluid by capillary action to the reagent material. If a given substance is present in the body fluid, the reagent chemically reacts with that substance. The reaction of the reagent, upon contact with the body fluid, can be analyzed (e.g., electrochemically or optically) to determine the presence and/or concentration of a particular substance.
Many test strip reagents are sensitive to the effects of ambient humidity and sunlight. One way to reduce or eliminate the effects of humidity and sunlight is to individually package each of the sensors with desiccant. Individually packaging each strip, however, increases manufacturing time and costs, and inflates packaging and shipping costs, all of which result in increased costs to the end user. To reduce costs and improve ergonomics, containers have been designed to store and dispense multiple test sensors, thereby eliminating the need to individually package each test strip. Examples of some containers for storing a stack of test sensors can be found in U.S. Pat. Nos. 7,677,409, 7,875,243, 8,097,210 and 8,153,080, and U.S. Patent Appl. Pub. No. US2013/0324822 A1, each of which is incorporated herein by reference in its entirety. Many of these containers enclose the sensor stack in a hermetically sealed, rigid outer housing. Some of the containers are provided with a mechanical dispensing mechanism to feed the test sensors, one at a time, for testing by the user. This configuration provides ease of use to normal users and is especially important for those users who may have some physical limitations.
Shown respectively in FIGS. 1 and 2 are examples of a hand-held analyte testing device 10 (“meter”) and a package 30 of test strips 12 (“test strip pack”). The test strip pack 30 of FIG. 2 is designed to be housed within the analyte testing device 10 of FIG. 1. The testing device 10 has a display device 20 for displaying information (e.g., analyte concentration readings) to the user. The analyte testing device 10 also includes a slider 18, which cooperates with an “ejection” mechanism inside the testing device 10 for advancing test strips 12 from the package 30 for harvesting a sample of fluid. Prior to each test, an individual test strip 12 is pushed by the ejection mechanism through the package 30 such that a collection area 14 of the test strip 12 is extended from the testing device 10 through a slot 16 formed in the housing of the meter 10. As seen in FIG. 1, the collection area 14 projects from the testing device 10, while a contact area of the test strip 12 (visible in FIG. 2), which is disposed at the opposite end of the strip 12, remains inside of the testing device 10. In electrochemical configurations, the contact area includes terminals that electrically couple test strip electrodes to testing instrumentation disposed within the testing device 10. This instrumentation is configured to measure the oxidation current produced at the electrodes by the reaction of glucose and the reagent.
A circular array of test strips 12 is shown in FIG. 2 disposed inside of the test strip pack 30. The test strip pack 30 comprises a disk-like circular container 32 with ten individual compartments 34—referred to in the art as “blisters”—arranged radially on the circular container 32. The circular container 32 is made from an aluminum foil/plastic laminate which is sealed with a burst foil cover 36 to isolate the sensors 12 from ambient humidity, sunlight, and from adjacent sensors. Each test strip 12 is kept dry by a desiccant located inside a desiccant compartment 37 disposed adjacent to the compartment 34. Further details of the manufacture, configuration, and operation of the testing device 10 and test strip pack 30 are provided, for example, in U.S. Pat. Nos. 5,630,986, 5,575,403, 5,810,199 and 5,856,195.
A drawback associated with the circular array of test strips 12 of FIG. 2 is the large area that is required to house the test strip pack 30. Size restrictions for hand-held testing devices that internally house flat test strip packs constrain the size of the package, which restricts the number of test strips that can be provided in each package. Having a low number of strips in the disk results in a higher per strip cost for the package which is not desirable since in vitro diagnostic assays and, especially, glucose monitoring test strips are faced with continuing downward pressure on selling prices. Similarly, a drawback associated with conventional flip-top containers and screw-tight sensor bottles is the overall complexity of each container and the amount of material required to fabricate each container. In addition, the manual operations required for closing and opening test sensor bottles and for removing strips from the bottle is oftentimes not convenient, which discourages patient testing even though increased patient testing is associated with better glucose management. Customer convenience is another key factor in influencing compliance to a regular testing regimen. In addition, it is often necessary for a person with diabetes to test while “on the go” where manual manipulation of a bottle and strips can be very difficult. Finally, the large cylindrical foot print of a bottle necessitated by the need to retrieve strips by finger is not conducive to portability. What is needed then is a test sensor container configuration that can store a larger quantity of sensors in a small area, while maintaining customer convenience and offering low-cost manufacturing options for the sensor and packaging.